In slaughtering poultry, it is common to first stun the poultry, then kill the stunned poultry, and then to process the killed poultry. In stunning the poultry, it is desirable to avoid damaging the poultry tissue and to minimize movement of the poultry.
In known prior stunner systems, a pulsating low DC voltage has been applied. The pulsating DC voltage, usually in the 10-14 volt range for chickens, 14-18 volts for small turkeys, and 30-35 volts for larger turkeys, works well for most poultry processors. However such pulsating DC voltages are not acceptable for those localities requiring a so-called “stun-to-kill” approach.
In general, most stunners used outside North America are based upon a design developed in Western Europe. These European stunners operate as “water bath” stunners. This means that the birds' heads and necks are dragged through a tank of electrically charged water. This results in a very inconsistent stun, and, when combined with European style killing machines which cut only one side of the bird's neck, results in birds still being alive when reaching the scalder. This is the main reason that many European countries now require the “stun-to-kill” practice.
However, when a bird is killed in a stunner with electrical current, there is a very strong possibility of causing damage to the carcass, such as broken bones and hemorrhaging of blood vessels. Poultry processors have been looking for alternative stunning methods to improve the “stun-to-kill” procedure so that the birds can be stunned with less resulting product damage.
U.S. Pa. No. 6,019,674 of Simmons provided a step forward in the art. As described in his patent, a saline solution is contained in an elongated trough, which is mounted at the end portions of four non-electronically conducting posts. The trough is filled with saline solution. The trough has an ingress funnel arrangement designed to control the thrashing of to-be-electrically stunned birds and an elongated grid having a portion immersed in the solution and a downstream portion out of the solution. The four posts extend upwardly and terminate in threaded portions. A frame carriage is provided which has four corners, and at the four corners are suitably mounted driven gears with internal bores and threads adapted to engagingly rotate about the threaded portions of the ports. The carriage is suitably affixed to a conventional I-beam to which is movingly mounted a conventional endless cable and space shackle system for conveying birds in an upside down manner. The four mounted gears are rotatable in unison by a chain drive which may be manual, hydraulic, pneumatic or electric, whereby the trough may be selectively moved upwardly or downwardly as found necessary to vary the distance between the said I-beam and said trough to accommodate different sized shackles and/or birds.
The trough has a short extension bolted there onto to provide a first section and a second section. Both sections include a grate through which and across the top there of the bird's head is dragged.
In the first section, a pulsating DC current operating at a relatively low voltage (9-30 volts) is applied via an electrical connection, such that electricity is applied to a grate in each section. The overhead shackle line carrying the birds is at a polarity which is opposite to the polarity of electricity being supplied to the stainless steel surface submerged in saline solution and the trough. In the second section, a low AC current operating at about 30 volts is applied via the electrical connection between the shackles and the trough. The second section of the extension is electrically isolated from the first section of the main or first section of the trough. The speed of the conveyer is such that the poultry are subjected to the low voltage AC current in the extension for a period of only about two to three seconds.
While the apparatus and method described in U.S. Pat. No. 6,019,674 are effective to stun a bird such that it is unconscious, the bird is likely to still exhibit undesirable involuntary motion.